Gearbox with a housing which has a lower housing part, onto which an upper housing part is placed

ABSTRACT

A gearbox includes a housing, which has a lower housing part onto which an upper housing part is placed. The lower housing part and the upper housing part are in physical contact along a contact surface, for example, so that the contact surface between the lower and upper housing part lies in a plane and/or is planar. Cooling fins are situated on the housing, the cooling fins having a curved characteristic such that a portion of an axially directed airflow streaming along the housing, and thus in particular an airflow that is streaming parallel to the axis of rotation of the input shaft, is deflected in a transverse direction between two cooling fins disposed closest to each other in the axial direction in each case, the axial direction, for example, being parallel to the contact surface, e.g., the plane.

FIELD OF THE INVENTION

The present invention relates to a gearbox having a housing which has alower housing part onto which an upper housing part is placed.

BACKGROUND INFORMATION

Certain conventional gearboxes include a housing, which accommodatesbearings for the rotatable support of shafts.

SUMMARY

According to an example embodiment of the present invention, a gearboxincludes a housing having a lower housing part onto which an upperhousing part is placed, a lower housing part and an upper housing partare in physical contact along a contact surface, in particular so thatthe contact area between the lower and upper housing part is located ina plane and/or is planar, wherein cooling fins are situated on thehousing, which are provided in curved form such that a portion of anaxially directed airflow streaming along the housing, and thus inparticular an airflow streaming parallel to the axis of rotation of theinput shaft, is deflected in a transverse direction between two coolingfins situated closest to each other in the axial direction in each case,the cooling fins situated above the contact surface in particulardeflecting the respective portion of the airflow in the transversedirection, in particular in the vertical direction, and the cooling finssituated below the contact surface deflecting the respectively allocatedportion in a direction opposite to the transverse direction, the axialdirection in particular extending parallel to the contact surface, inparticular the plane.

The upper housing part need not be situated on top in the gravitationaldirection, i.e. above the lower housing part, but the gearbox may bearranged in any desired alignment. Therefore, the upper housing partshould be understood as a first housing part, and the lower part as asecond housing part. ‘Above’ then means on the particular side of thecontact surface on which the first housing part is situated, or in otherwords, above the space region that faces away from the second housingpart. ‘Below’ thus means in the space region of the contact surface thatfaces away from the first housing part.

This offers the advantage that the cooling fins, which are situated onebehind the other in the axial direction, trap and deflect multipleportions of the airflow, so that a more uniform heat dissipation of thegearbox is possible.

In example embodiments, the initial distance of the cooling finsmonotonically decreases in the axial direction, in particular inproportion to the axial position, or more progressively, the initialdistance of the respective cooling fin being the smallest distance tothe contact surface in each case, the axial position in particular beingthe distance to the axial end region of the gearbox disposed counter tothe axial direction. This has the advantage that the cooling fins thatare disposed at a greater distance in the direction of the airflow startcloser to the contact surface, that is to say, at a smaller initialdistance. A monotonic decrease in the initial distances has the effectthat the between two closest to each other is always an equally wideportion of the airflow, and thereby makes it possible to achieve auniform distribution of the airflow.

In example embodiments, the initial distance of the cooling fins in theaxial direction is inversely proportional to the axial position. Thisoffers the advantage that the initial distance progressively decreaseswith increasing distance from the fan which is driving the airflow, sothat a virtually constant volumetric flow is able to be conveyed betweentwo cooling fins situated closest to each other in each case.

In example embodiments, a fan is situated on the gearbox, in particulara fan which is connected in a torsionally fixed manner to the inputshaft, the fan induces the axially directed airflow along the housing,the quotient of a first difference and a second difference isproportional to the quotient of a second velocity to a first velocity,the first difference is the difference amount of the initial distancesof two cooling fins situated closest to each other in the axialdirection in each case, and the airflow has the first velocity, i.e.flow velocity, when the airflow enters between the cooling fins, and thesecond difference is the difference amount of the initial distances oftwo further cooling fins situated closest to each other in the axialdirection in each case, and the airflow has the first velocity, i.e.flow velocity, when the airflow enters between these further coolingfins. This offers the advantage that a uniform distribution of theairflow is achievable because an identical portion is conveyed in eachcase between two cooling fins situated closest to each other. This makesit possible to achieve a substantially uniform heat dissipation from thegearbox.

In example embodiments, the lower housing part resembles the upperhousing part. This offers the advantage that a multitude of gearboxesmay be produced using a low number of parts.

In example embodiments, a first number of cooling fins is situated abovethe contact surface, and the remaining cooling fins are situated belowthe contact surface, the first number in particular being equal to thenumber of the remaining cooling fins. This offers the advantage that thegearbox is cooled in a symmetrical, i.e. uniform, manner.

In example embodiments, the cooling fins are arranged in two pieces orin multiple pieces, and a respective first piece is provided on one ofthe two housing parts, and a respective further piece is provided on abearing cover, an air gap, in particular, being situated between therespective first piece and the respective further piece. This isconsidered advantageous insofar as the bearings are able to be coveredby a bearing cover while a uniform heat dissipation is achievablenevertheless.

In example embodiments, the curved characteristic of the cooling finssituated above the contact surface is provided in mirror symmetry withthe curved characteristic of the cooling fins situated underneath thecontact surface in relation to the contact surface. This has theadvantage of allowing for a simpler production.

In example embodiments, the contact surface is planar, that is to say,encompassed by a plane, in particular. This offers the advantage thatuncomplicated sealing may be implemented between the upper and the lowerhousing part.

In example embodiments, the cooling fins situated on the housing arepositioned and curved such a way that the same volumetric airflow isconveyed between two cooling fins situated closest to each other in theaxial direction in each case, or in other words, the distance in theaxial direction between the two cooling fins situated closest to eachother in the axial direction increases with an axially greater position,in particular in accordance with or in proportion to the inflow velocityof the airflow into the region between two respective cooling fins. Thishas the advantage of achieving the most uniform heat dissipationpossible.

Further features and aspects of example embodiments of the presentinvention are described in greater detail below with reference to theappended Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a gearbox whose housing includes a lower housing part 4 andan upper housing part 1, which is placed on top.

FIG. 2 shows a gearbox including a fan 5.

DETAILED DESCRIPTION

As illustrated in FIG. 1, the two housing parts 1 and 4 have the samedesign, i.e. the same configuration.

The two housing parts 1 and 4 include bearing seats in each case, whichare able to accommodate bearings for the support of an input shaft, anoutput shaft, and two intermediate shafts, two toothed components beingconnected to the intermediate shafts in a torsionally fixed manner, andonly one toothed component in each case being connected to the inputshaft and to the output shaft.

As illustrated in FIG. 1, the input gear stage is arranged as aright-angle gear stage and is driving two parallel shaft gear stages sothat the two intermediate shafts and the output shaft including theirbearings are covered by bearing cover 2 on the side.

The interior space of the gearbox is filled with lubricating oil, sothat the tooth systems that are in engagement with one another arelubricated by lubricating oil.

Cooling fins 3 for the dissipation of heat are provided, which arecomposed of a plurality of parts. Each cooling fin 3 includes at leasttwo parts. A first part of the respective cooling fin 3 is situated onbearing cover 2 and a second part is situated on the respective housingpart 1 or 4.

Upper housing part 1 is connected to the lower housing part 4 along acontact surface, in particular a contact plane.

Each cooling fin has a curved characteristic starting at the contactsurface, so that an incoming airflow that streams along the contactplane in the axial direction, i.e. parallel to the direction of the axisof rotation of the input shaft, and along the housing of the gearbox, isdeflected in an upward or downward direction.

The curved characteristic of the respective cooling fins 3 begins at aninitial distance from the contact surface and ends at a greater finaldistance. The distance from the contact surface increases monotonicallyalong cooling fin 3. For example, the characteristic of cooling fins 3is such that the gradient also increases monotonically with the distancefrom the contact surface.

The wall thickness of the respective cooling fin 3 may be substantiallyconstant. An air gap is provided between the region of the respectivecooling fin 3 situated on bearing cover 2 and/or provided thereon, andthe region of respective cooling fin 3 situated on the upper or lowerhousing part (1, 4). This air gap may be configured to be as small aspossible.

The values of the respective initial distances of cooling fins 3decrease monotonically in the axial direction, the initial distance ofthe final cooling fin 3 even vanishing, in particular so that finalcooling fin 3 of upper housing part 1 and final cooling fin 3 of lowerhousing part 4 come very close to each other or even touch.

As illustrated in FIG. 2, it is also possible to provide a fan whoseairflow streams along the outer sides of the gearbox in the axialdirection. Because of curved cooling fins 3, a respective portion of theconveyed airflow is deflected in the transverse direction, the coolingfins 3 of upper housing part 1 deflecting the respective portion in anupward direction, and cooling fins 3 of lower housing part 1 deflectingthe respective portion in a downward direction.

In the example embodiment illustrated in FIG. 1 and FIG. 2, the initialdistance of cooling fins 3 in the axial direction decreases inproportion to the axial distance from the end face of the gearbox. Inthe exemplary embodiment according to FIG. 2, the end face of thegearbox is the side of the gearbox that is facing the fan. Because ofthe proportional dependence on the axial distance, a portion of theairflow which always has the same width is deflected between two coolingfins 3 of the respective housing part (1, 4) that are closest to eachother in each case.

In further exemplary embodiments, the initial distance of cooling fins 3has a dependence on the axial direction according to a function of ahigher order, in particular according to a square function. The portionof the airflow deflected between two cooling fins 3 of respectivehousing part 1 or 4 closest to each other therefore has a width thatincreases with the axial distance when viewed in the transversedirection to the axial direction. However, since the flow velocity ofthe respective deflected portion decreases with increasing axialdistance, the deflected volumetric airflow, as the respective deflectedvolume per time, is as constant as possible.

In this manner, the most uniform distribution possible of the coolingoutput is achievable on the particular side surface of the gearbox alongwhich the airflow is streaming.

In further exemplary embodiments, fan 5 is disposed on the input shaftin a torsionally fixed manner and therefore conveys the airflow counterto the axial direction. Similar to the afore-described exampleembodiment, the initial distances of the cooling fins thus decreasecounter to the axial direction in proportion to an increasing axialdistance from the input shaft, in particular from the bearing of theinput shaft, or progressively such that the portion of the airflow,particularly conveyed by the fan, deflected between two cooling fins 3in each case induces an identical volumetric flow.

In order to ensure that the volumetric flow is immediately identical intwo different portions, the differences of the initial distances ofadjacent cooling fins 3 may exhibit an inversely proportional behaviorto the velocities of the airflow exhibited by the airflow when it isstreaming into the intermediate regions between the two adjacent coolingfins in each case. The following therefore applies:

Da1/Da2=v2/v1

where Da1 is the difference amount of the two initial distances of twocooling fins 3 situated closest to each other in the flow direction, andDa2 is the difference amount of the two initial distances of two coolingfins 3 situated closest to each other in the flow direction, which are,for example, set apart from cooling fins 3 allocated to Da1 in the flowdirection, v1 being the flow velocity of the airflow in the inflowregion between cooling fins 3 allocated to the two Da1, and v2 being theflow velocity of the airflow in the inflow region between cooling fins 3allocated to the two Da2.

The curved characteristic of cooling fins 3 has a gradient thatincreases in the flow direction so that the gradient, which initiallyhas a virtually parallel orientation with respect to the flow direction,gradually increases, or in other words, inclines more and more, in thetransverse direction.

In further exemplary embodiments, further cooling fins are provided inaddition. These further cooling fins may be situated outside the regionof cooling fins 3, i.e. they are not situated between two cooling fins 3in each case.

In further exemplary embodiments, the gearbox is aligned in a differentorientation. The upper housing part need not be situated on top in thegravitational direction, i.e. above the lower housing part, but thegearbox may be arranged in any desired alignment. Therefore, the upperhousing part should be understood as a first housing part, and the lowerpart as a second housing part. ‘Above’ then means on the particular sideof the contact surface on which the first housing part is situated, orin other words, the space region that faces away from the second housingpart. ‘Below’ thus means in the space region of the contact surface thatfaces away from the first housing part.

LIST OF REFERENCE NUMERALS

1 upper housing part

2 bearing cover

3 cooling fin

4 lower housing part

5 fan

1-10. (canceled)
 11. A gearbox, comprising: a housing, including a firsthousing part and a second housing part, the first housing part and thesecond housing part being connected by screws, the first housing partand the second housing part in physical contact along a contact surface;wherein the housing includes curved cooling fins adapted to deflect atleast a portion of an axially directed airflow streaming along thehousing and/or an airflow streaming parallel to an axis of rotation ofan input shaft in a respective transverse direction between two coolingfins located closest to each other in an axial direction, the axialdirection being parallel to the contact surface.
 12. The gearboxaccording to claim 11, wherein the cooling fins arranged on a first sideof the contact surface are adapted to deflect a respective portion ofthe airflow in a first transverse direction and the cooling finsarranged on a second side of the contact surface, opposite the firstside of the contact surface, are adapted to deflect another respectiveportion in a second transverse direction that is opposite to the firsttransverse direction.
 13. The gearbox according to claim 12, wherein thefirst transverse direction and the second transverse direction arevertical.
 14. The gearbox according to claim 13, wherein the axialdirection is horizontal.
 15. The gearbox according to claim 11, whereinthe contact surface is located in a plane and/or is planar.
 16. Thegearbox according to claim 15, wherein the axial direction is parallelto the plane.
 17. The gearbox according to claim 11, wherein an initialdistance of the cooling fins monotonically decreases in the axialdirection, the initial distance corresponding to a smallest distance ofthe cooling fin from the contact surface.
 18. The gearbox according toclaim 17, wherein the initial distance of the cooling fins monotonicallydecreases in the axial direction and/or more progressively in relationto an axial position.
 19. The gearbox according to claim 18, wherein theaxial position corresponds to a distance to an axial end region of thegearbox located counter to the axial direction.
 20. The gearboxaccording to claim 11, wherein an initial distance of the cooling finsin the axial direction is inversely proportional to a axial position,the initial distance corresponding to a smallest distance of the coolingfin from the contact surface, the axial position corresponding to adistance to an axial end region of the gearbox located counter to theaxial direction
 21. The gearbox according to claim 11, furthercomprising a fan provided on the gearbox and adapted to induce anaxially-directed airflow along the housing, a quotient of a firstdifference and a second difference being proportional to a quotient of asecond velocity to a first velocity, the first difference being adifference amount of initial distances of two cooling fins situatedclosest to each other in the axial direction, the airflow streamingbetween the cooling fins having the first velocity, the seconddifference being a difference amount of the initial distances of twofurther cooling fins situated closest to each other in the axialdirection, and the airflow streaming between the two further coolingfins having the second velocity.
 22. The gearbox according to claim 21,wherein the fan is connected to the input shaft in a torsionally-fixedmanner.
 23. The gearbox according to claim 11, wherein the first housingpart and the second housing part are identical housing parts.
 24. Thegearbox according to claim 11, wherein a first number of cooling fins isarranged on the first side of the contact surface, and remaining coolingfins are arranged on the second side of the contact surface.
 25. Thegearbox according to claim 24, wherein an equal number of cooling finsare arranged on the first side of the contact surface and on the secondside of the contact surface.
 26. The gearbox according to claim 11,wherein each cooling fin is formed of at least two pieces including afirst piece molded on one of the housing parts and a second piece moldedon a bearing cover.
 27. The gearbox according to claim 26, wherein anair gap is provided between corresponding first and second pieces ofeach cooling fin.
 28. The gearbox according to claim 11, wherein thecooling fins located on the first side of the contact surface are mirrorsymmetrical, with respect to the contact surface, to the cooling finslocated on the second side of the contact surface.
 29. The gearboxaccording to claim 11, wherein the cooling fins are configured andcurved to convey an identical volumetric airflow between two coolingfins situated closest to each other in the axial direction, a distancein the axial direction between the two cooling fins situated closest toeach other in the axial direction increases, with an axially greaterposition, in accordance with, and/or in proportion to an inflow velocityof the airflow into a region between two respective cooling fins.